改善空载电压波形是发电机优化设计、保证电能质量的重要问题。采用极靴偏心与阻尼条偏心等不对称磁极结构设计方案，对一台45 MW的大型水轮发电机空载电压波形进行优化设计，并利用二维运动电磁场场路耦合时步有限元模型，进行分析与计算。结果表明，合理偏移极靴和阻尼条位置，可以明显削弱齿谐波，改善气隙磁场分布和空载电压波形。计算结果与实测数据相吻合。研究成果已在3个电站的大型水轮发电机上得到工程实际应用。

The improvement of no-load voltage waveform is an important problem for design optimization of generators and ensuring the quality of electric power. The no-load voltage waveforms of a 45 MW hydro-generator are optimized with the asymmetric poles design including the eccentricity of the pole shoes or/and the damper bars, and the optimization is implemented and analyzed by 2D moving electromagnetic field-circuit coupling model. The results show that the tooth harmonics are weakened obviously, the waveforms of the air gap magnetic field and the no-load voltage are improved when reasonable shifting the center of the pole shoes or/and the damper bars. The calculation results are coincident well with the test data. The research has been applied to 3 large hydro-generators operating at the power stations.